Hydraulic servo motor



y 1933- G.-.OPLUSSTIL I 1,917,055

HYDRAULIC SERVO MOTOR Filed Dec. 24, 1930 2 Shgets-Sheet 1 Y .FILM.

1F FIG.2. w 39 273133 '38 4 1+. 45 FIG. 3.

Inventor;

I f Witnesses:

July 4, 1933. o uss n 1,917,055

HYDRAULIC SERVO MOTOR Filed Dec. 24, 1950 2 Sheets- -Sheet 2 Witnesses: Inventor:

Patented July 4, 1933 UNITED STATES PATENT OFFICE GUSTAV OPLUSSTIL, or BRUNN, ozEoHosLovAKrA, ASSIGNOR ro- FIRM mm s'roanx,

- or BRUNN, ezEcnosLovAKIA mimetic SERVO moron Application filed December 24, 1930, Serial No. 504,474, and in Czechoslovakia February 21, 1930.

The use of hydraulic servo motors for ad-- the rotating servo motor .so that it is not necessary tointroduce the pressuremedium into the rotating parts from outslde. Arrangements have been found particularly 'advantageous and simple in which the compressor is built into the working piston of the servo motor and is slidable together with it, the working piston itself forming the means for restoring the original position.

Some constructional examples of, the invention are illustrated in the accompanying drawings.

Fig. 1 shows an axial sectionof a servo motor according to' the invention, Fig. 2

shows a section of a modified control arrangement on a larger scale, Fig. 3 is the same section for another position of the control member, Fig. 4 is a section on the line IV-IV of 'Fig. 1, Fig. 5 isan axial section of a servo motor with the modified control arrangement shown in Figs, 2'and 3.

In Figure 1, 1 is the rotating working cylinderrigidl connected with the hollow shaft-2. 3 is t e working piston slidable in the working cylinder and rotating with it. on account of the key 4,-w1thits piston rod 5. 6 and 7 are two rotary pumps arranged 1n.

the piston 3 which are driven by-the non rotating toothed wheel 8 as soon as the preton 3 is turned. The-toothed wheel 8 is mounted on a tube '9.which is guided slidably in a stationary part 11' by the key 10. Inside the tube 9 is aslide valve 12 which may be displaced axially from the outside. Between its leading edges 13 and 14' is a space '15 which serves as suction. space for. the pumps '6 and 7, and is connectedwithzthem through the suction channels 16 and 17. From the pump 6 a pressure channel 18 leads to the cylinderspace A and from the pump 7 a pressure channel 19 leads to the cylinder space B.

The places where the suction and pressure.

channels are attached to the pumps are only illustrated diagrammatically in order to make the drawings more clear. The most suitable position depends on the construction of the pumps used.

Borings 20 and 21 connect the cylinder spaces B and-A with the suction space 15 through the intermediary of annular recesses as-long as the leading edges 13 or 14 do not interruptthis connection. In the neutral position of the slide valve 12 both edges 13 and 14 leave a free passage.

The apparatus operates as follows When the cylinder 1 rotates with the piston 3 the pump wheels 6 and 7 roll round the stationary tothed wheelS. They thus rotate relatively to the piston 3 and each produces a circulation of the pressure fluid which fills all the hollow spaces of the apparatus. The pump'6sucks out of the space 15 through the channel 16, forces the working fluid through the channel 18 into the cylinder space A and from there through the borings 21 back into the suction space 15. The circulation *of the pump 7 is the following: suction chamber 15, suction channel 17, pump wheel 7, pressure channel 19, cylinder space B, borings 20, suction space 15. These circulations do not cause any alteration of the position of the working piston with respect to the working cylinder.

When the servo motor is to come into operation, the slide valve 12 is displaced axially,

for example towards the right. The lead-' ing edge 14: then cuts ofl the return of the pressure medium delivered by the pump 7 to the suction chamber 15 and thus interrupts the circulation. The pressure fluid delivered into the cylinder space B causes'there an increase of pressure and displaces the piston3towards the right. The circulation of the pump 6 isnothindered by the displacement of the slide valve 12, because the leadin edge 13 has left a large passage open.

s' t e working piston 3,through the action of the pump 7, completes its movement to the right, thus following the slide valve 12, it gradually restores the original relative position. In an analogous manner the working piston is moved to the left by the pump 6 Evhen the slide valve 12 is displaced to the le t.

If the working piston has to overcome large resistances to its motion, an undesirably great heating of the pressure fluid may occur. If the slide valve 12 is displaced towards the right, so that the leading edge 14 closes the channel 20, the pump 7 will deliver into the space B and will displace the piston 3 to the right, so that the pressure in this space will become as high as is necessary to overcome the resistance of the piston. As soon as the i piston 3 has gone so far to the right that the edge-14 again begins to open the channel 20, the fluid from the space B will flow through the narrow slot at the edge 14 into the suction chamber 15 with a high velocity, and this state will continue as long as the slide valve 12 remains in the same position. As a result of the throttled flow, the pressure fluid may be overheated.

Figures 2 and 3 show diagrammatically to a larger scale and in two positions, acontrolling device which avoids the disadvantages referred to. Similar parts have the same reference characters as in Figure 1.

The slide valve 12 is here surrounded by a control sleeve 22 with leading edges 39 and 40 which, by means of the rings 23, 24 and the. springs 25, 26, is normally held' in the position shown in Figure 2. The; control sleeve 22 can however slid a little way along the slide valve 12 again t the springs 25 or 26. Between the sleeve 22 and the slide valve 12 the chambers 27, 28, to which the channels 29, 30 lead, are arran ed. These chambers are also connected with the exterior of the control sleeve through the channels 31, 32, the grooves 33, 34 of the slide valve 12 and the channels 35, 36. I

The tube 9, in which the sleeve 22 slides, has annular channels 37, 38 which are connected with the suction space 15 in addition to the channels 21, 20 shown in Figure 1.

The apparatus works as follows If the slide valve, which is illustrated in the neutral position in Figure 2, is displaced to the right by an amount so, the leading edge 40 will cut oil the channel 20. Since here the pump 7 delivers into the space B with which the channel 20 is connected, the pressure here will rise. The pressure fluid is forced through the channel 36 into the annular groove 34 and from there through the channel 32 into the. space 28. Since the channel 30 is shut off from the groove 38,

' the pressure rises in the chamber 28 and the control sleeve 22 is displaced to the right, the spring 26 being tensioned until the connection between the annular groove 34 and the channel 36 is not completely interrupted by the slide valve 12. Since the chamber 27 communicates with the suction chamber 15, the fluid will be forced out of it. The leading edge 40 however has also been displaoedto the right a distance y, that is, in adjusting the slide valve 12' a distance :23 a total displacement a;+g is produced. This position corresponds to Figure 3.

The working piston 3 and with it the tube 9 now move to the right, the channel 20 being shut off without a throttling flow, and without heating of the fluid taking place at the edge 40. At the moment when the edge 40 begins-to open the channel 20 again, and. when the undesirable throttling flow does take place in the gap being formed, the channel 30 has also made a connection between the space 38 and the chamber 28, so that the pressure in the latter falls. The spring 26 then moves the control sleeve 22 back into its neutral position according to Figure 2. A continued throttled flow of the fluid at the edge 40 is thus avoided.

A similar action may be obtained with the arrangement according to Figure 1 if the slide valve 12 is first moved towards the right to a rather larger extent than corresponds to the desired movement of the piston. If the piston 3 is then moved back this distance, the channel 20 being closed, and has reached the position in which the throttled flow at the edge 14 would begin, the slide valve. 12 only requires to be displaced a little way back towards the left in its neutral position. Since in most cases the working resistance of the piston consists chiefly of frictional forces, the piston 3 remains in the new position even when the pressure in the space B has so far diminished that no perceptible throttling can take place at the edge 14. The control according to Figures-2 and 3 regulates the process described automatically for both directions of displacement.

The constructional examples illustrated do not exhaust the idea underlying the invention, but numerous arrangements are possible within the scope. The kind and arrangement of the elements which drive the pumps are I similarly not limited. Finally the field of use of the invention is not limited to regulating the rotors of water turbines, but includes all the cases in which machine parts belonging to a rotating system have to be adjusted during operation.

What I claim is: y

1. A hydraulic servo-motor, comprising a rotating'casing, a piston rotating with the casing and movable therein under'the action of compressed fluid, means for transmitting the force of the piston to the outside of the casing, a control device for controlling the supply of fluid to the sides otthe piston, a pump device built into the rotating servomotor and means for driving the pump device,

distinct from those which transmit the force of the piston.

2. A hydraulic servo-motor, comprising a rotating casing, a piston rotating with the casing and movable therein under the action of compressed fluid, means for transmitting the force of the piston to theoutside of the casing, a control device for controlling the supply of fluid to the sides of the piston, a

pump device built into the piston, and means for driving the pump device, distinct from those which transmit the force of the piston.

33. A hydraulic servo-motor, comprising a rotating casing, a piston rotating with the casing and movable therein under the action of compressed fluid, means for transmitting the force of the piston to the outside of the casing, .a control device for controlling the supply of fluid to the sides of the piston, a pump device for each direction of movement of the piston, built into the rotating servomotor and means for driving the pump devices,-distinct from those which transmit the force of the piston.

4. A hydraulic servo-motor, comprising a rotating casing, a piston rotating with the casing and movable therein under the action of compressed fluid. means for transmitting the force of the piston to the outside of the casing, a control device for controlling the supply of fluid to the sides of the piston, a pump device for each direction of movement of the piston, built into the rotating servomotor, both pumps having a common suction space, and means for driving the pump device, distinct from those which transmit the force of the piston.

5. A hydraulic servo-motor, comprising a rotating casing, a piston rotating with the casing and movable therein under the action of compressed fluid, means for transmitting the force of the piston to the outside of the casing, a control device for controlling the supply of fluid to the sides of the piston and two rotary pumps, having a toothed wheel in common which also serves for driving the of fluid to the sides of the piston, a controlling sleeve slidably mounted on the slide valve. a chamber being provided between the slide valve and the sleeve for each direction of displacement of the sleeve, whereby by admission of fluid under pressure the sleeve can be displaced on the slide valve, a spring between the slide valve and the controlling sleeve for each direction of displacement of the controlling sleeve adaptcd to return the controlling sleeve to its original position on the slide valve at the end of the movement of the piston in the direction of movement of the slide valve, a pump device built into the rotatin g servo motor and means for driving the pump device, distinct from those which trans niit the force of the piston.

7. A hydraulic servo-motor, comprising a rotating casing, a piston rotating with the casing and movable therein under the action of compressed fluid, means for transmitting the force of the piston to the outside of the casing, a slide valve for controlling the supply of fluid to the sides of the piston, a controlling sleeve slidably mounted on the slide valve, a chamber being provided between the slide valve and the sleeve for each direction of displacement of the sleeve, whereby by admission of fluid under pressure the sleeve can be displaced on the slide valve in the direction of movement of the slide valve, a pump device built into the rotating servomotor and means for driving the pump device, distinct from those which transmit the force of the piston.

In testimony whereof I have signed my name tothis specification.

GUSTAV 'OPLUSSTIL. 

